1. Field of the Invention
The present invention relates to an apparatus for controlling the charging of a storage battery for use as a drive energy source on an electric vehicle, and more particularly to such a storage battery charging control apparatus capable of finishing the charging of a storage battery at a scheduled time for boarding the vehicle.
2. Description of the Related Art
Chargers for charging storage batteries for use on electric vehicles generally have a charging start command key for starting to charge the storage battery and a charging stop command key for stopping charging the storage battery. The storage battery starts being charged when the charging start command key is manually pressed, and the charging of the storage battery is stopped when the charging stop command key is manually pressed.
It has been proposed to charge storage batteries for use on electric vehicles with electric energy that is available from a commercial electric energy supply system at a discount night rate. For charging the storage batteries with electric energy available at the night rate, it has also been proposed to employ a timer which allows the charging electric energy to be supplied only in a night time zone in which the electric energy is available at the discount night rate.
When the storage battery on an electric vehicle is to be charged at home or in a business facility, it is often customary to connect a charger to a power supply outlet to start charging the storage battery at the same time that the electric vehicle is parked because it is time-consuming to charge the storage battery.
If the storage battery is charged prior to a day on which the electric vehicle is not used, e.g., on a weekend, then the storage battery is left to stand for a long period of time from the end of the charging process to the start of driving of the electric vehicle, and the charged storage battery tends to be self-discharged during that period of time.
Another problem is that while the temperature of the storage battery is high immediately after it is charged, the temperature of the storage battery drops soon in a cold climate after having been left to stand for a long period of time, thereby adversely effecting the discharging characteristics of the storage battery and resulting in a virtual reduction in the storage capacity of the storage battery. This problem manifests itself with general lead storage batteries.
Users of electric vehicles tend to start charging the storage batteries on the electric vehicles at the end of work in the evening or after going home. This charging practice poses a problem because it increases demands for electric energy and hence produces a peak of demands for electric energy in that time zone.